For the first time ever, Amazon has released viewership numbers for its various original programs. Well, kind of. Somehow, Reuters got their hands on an Amazon internal document that compares metrics for 19 Amazon Prime Originals, and now that they’ve published their findings, eager fans finally know how many people are watching their favorite shows — and whether these shows are in danger of being cancelled by the streaming giant.

In a not-totally-shocking twist, Amazon has a unique way of measuring a show’s success. Rather than focus purely on viewership numbers, the company bases their streaming decisions on whether a show pushes viewers to sign up for a Prime membership. Because viewers can only access Prime Originals and Amazon licensed content with this Prime membership, the company relies on a “first stream” metric to judge the relative success of any given show: the more people who stream something like The Man in the High Castleor Transparentimmediately after signing up for Prime, the more profitable (and therefore successful) Jeff Bezos & Co. deem that show.

Photo: Amazon Studios

According to Reuters, 26 million customers have watched a Prime Original or Amazon licensed show (something that Amazon picks up from a company rather than creates itself) from late 2014 to early 2017, the period of time covered by the Amazon document Reuters acquired. Using the first stream metric, Amazon estimates that the 19 Prime Originals included in the document accounted for about a quarter of total Prime sign-ups during this roughly three-year period, marking an incredible gain for a company that already seems to be taking over the world. The streaming/online retailer spends about $5 billion per year on its Prime Video content, and based on their returns, this kind of spending definitely seems justified.

As far as individual shows go, big-budget projects like The Man in the High Castle and the upcoming Lord of the Rings prequel have been proven to draw more new Prime customers than their more critically-minded peers. As of early 2017, Season 1 of The Man in the High Castle had 8 million U.S. viewers, and was estimated to attract 1.15 million new Prime subscribers worldwide — or first streams. The document shows that Amazon takes the total cost of the season (in this case, $72 million) and divides by the number of first streams it has (1.15 million) to calculate how much it cost to bring in each individual viewer. For TMITHC Season 1, it cost about $63 to bring in each new viewer, but considering that a year-long U.S. Prime membership costs $99, Amazon is raking in a $30-plus profit on each viewer. Another popular show, The Grand Tour, costs Amazon only $49 per viewer (it cost $78 million to produce, but had more than 1.5 million first streams).

On the other end of the spectrum, however, are Prime Originals like Good Girls Revoltand Sneaky Pete, which are losing A LOT of money for Amazon. Season 1 of Good Girls Revolt cost $81 million total to produce, but with only 52,000 first streams, it was costing Amazon over $1,500 per new customer. Naturally, Amazon cancelled the series after its first season. Sneaky Pete Season 1 fared slightly better, but not much: it cost Amazon $93 million to produce and market, but it ended up costing $959 per new customer once first streams were factored in. While Amazon didn’t give up on Sneaky Pete after its evidently lackluster first season, it will definitely have to bring in more new viewers with Season 2. If not, it will probably be heading to the chopping block.

If Amazon is going to base its creative decisions solely on the first stream metric, it makes sense that it chose to spend a massive sum of money on The Lord of the Rings prequel. According to Reuters, Amazon spent a cool $250 million on the rights alone, but production and marketing for the series could raise the total price to $500 million for two seasons. This number is triple what Amazon paid for Season 1 and 2 of The Man in the High Castle, so by Reuters’ estimates, it would need to grab just under 4 million new customers (3 times the number of Prime members brought in from Season 1 and 2 of TMITHC) for Bezos’ company to consider it worthwhile financially. 4 million may seem like a huge number of new Prime customers, it’s peanuts compared to Amazon’s current membership numbers: more than 75 million people have Prime accounts worldwide, including half of all U.S. households.

If anything is going to sway 4 million more Americans to get Prime, we’re thinking that a Game of Thrones-style epic will do the trick.